Very unscientific test regarding PSUs and wattage

[Octopuss]

My specs are in my profile.
I managed to destroy my own UPS so I grabbed the one we bought for my wife. It can also show the current power draw (which might not be 100% accurate, but I think it's accurate enough), so I felt like experimenting a little bit, mostly because of the neverending discussion about how high rated PSU you should buy (we're only talking single graphic card setups here).
There are many articles that explain how all of the more watts=better is complete bullshit, but people still know better. Well, let's take a look at my real world example.
I chose Prime95 and FurMark as I believe these will stress a PC as much as humanly possible (feel free to disagree). I also tried BF4 for a little more realistic situation.

I previously used some online calculators to get a rough idea how much power might my PC possibly draw, and now, to my surprise, it's not even close to what the PSU is rated for (and even more so in realistic situation).



P.S. Fun fact last - the reported power draw was including the monitor.

 

[metalslaw]

Sounds about right actually.

Most simple systems these days don't need more than a 500-600w power supply (depending on graphics card).

Anyway, thought I might add some info to this thread that I have found.



I have seen graphs with power draw while gaming, where a graphics card will sometime pull more watts for a small portion of time. (see inserted graph from http://www.tomshardware.com/reviews/radeon-r9-290-and-290x,3728-4.html) - note, there are regular 290's on that page too for comparison.

It stands to reason that the peak power draw of using an "approximate" of prime95+furmark is the max draw your system will do, and the number should be around a maximum of about 85% of the psu's rating. And providing the rating is true (i.e. a quality power supply), then the system will have 0 problems with this occasional power draw bursts.

Even some quality power supplies (e.g. seasonic) can take more than their rated max without failing. Here's a quick example, http://www.hardwaresecrets.com/article/Seasonic-X-Series-750-W-Power-Supply-Review/1591/7

Basically, any system builder is better off reading reviews, and finding a quality power supply that match their systems needs, than just buying any old '750w blue led' power supply that would probably have trouble getting past 450w... (oh damn, wrong thread... brb, gonna post a link to this )

Cheers,
metal

 

[AsRock]

Looks about right to me, having a system close your build.

And i know people disagree with my way of thinking about over sizing the PSU to put less stress on a PSU,

My usages are around 70-80w idle, gaming 170w-350w ( mostly 200w w/vsync ) and 450w with OCCT PSU test 450w.

All so over sizing a PSU can allow to run 2 GFX cards. although i just don't like running a system that can take 80%+ of what the PSU is rated for and with places like Newegg crazy sales on PSU's as i got mine for $90 with a 7 year warranty.

Never mind the rating being so good it was a none brainer.

EDIT:
Just to note my 6970 was taking the same power usage as i typically use vsync and with the last updates to a Arma 3 and Watch Dogs even with vsync off i don't even hit the 350w any more.

 

[Octopuss]

A wise man once said "750W is not always 750W"

 

[Caring1]

The reason I choose PSU's with a rating higher than is calculated that way is for the amperage on the rails for graphics.
Most cheap power supplies don't have enough for modern cards.

 

[krusha03]

For my system i have found that extreme power calculator is pretty accurate. According to partpicker my consumption should be 430W. And I do get this with my CPU overclocked, GPU at +20% power and running furmark + prime95. I get about 520W from the plug which results to about 430W for the system with a PSU efficiency of 83%. With the extreme power calculator when i input my config + the overclock i get 434W minimum PSU at 100% load and 100% TDP (522W from plus with 83% efficiency) which sounds correct. However as I said this high number i have only seen with Prime + Furmark. OCCT PSU for example gives me about 480W, AIDA stability testing with all except HDD about 380W, and BF4 about 350W from the plug. All other benchmarks use less. So that 90% tdp + 90% load is a good estimate of what your system would use under "normal use" full load (in my case 380W).

My PSU does get hot at full load and I would guess this is not good for the lifetime of the unit. For best efficiency you should be at about 50% of the rated load but I personally would feel comfortable using it up to 75-80%. However the higher you go the higher the temperature of the unit and the noise produced by it (which for me is not a concern since my 7950 sounds like a jet engine and pisses me off enough that i have to use headphones anyway ).

Edit: What is the point of this thread again?

 

[AsRock]

A wise man once said "750W is not always 750W"

Although a wise man all so checked the reviews, and when that was not true it was for the better.
http://www.techpowerup.com/reviews/Seasonic/X-750/5.html

Ya just have to wait out for those kick ass Newegg deals.

 

[claylomax]

My specs are in my profile.
I managed to destroy my own UPS so I grabbed the one we bought for my wife. It can also show the current power draw (which might not be 100% accurate, but I think it's accurate enough), so I felt like experimenting a little bit, mostly because of the neverending discussion about how high rated PSU you should buy (we're only talking single graphic card setups here).
There are many articles that explain how all of the more watts=better is complete bullshit, but people still know better. Well, let's take a look at my real world example.
I chose Prime95 and FurMark as I believe these will stress a PC as much as humanly possible (feel free to disagree). I also tried BF4 for a little more realistic situation.

I previously used some online calculators to get a rough idea how much power might my PC possibly draw, and now, to my surprise, it's not even close to what the PSU is rated for (and even more so in realistic situation).

View attachment 62698 View attachment 62699 View attachment 62697 View attachment 62700 View attachment 62696

P.S. Fun fact last - the reported power draw was including the monitor.

That's similar to the power consumption I get in my system.
Now overclock that 290 adding some voltage and do the tests again; I bet you will trigger the OCP in your psu and your pc will shut down.

 

[Octopuss]

Yeah, but that's not the point. The point is you don't need overhyped 700W+ PSU for higher end PC as lots of sources say.

 

[metalslaw]

Yep, the quality of the power supply often makes up for buying a 'lower wattage' psu from the chosen 'quality' manufacturer's lineup.

For instance, I recently built a new pc with a 750w antec High Current Gamer Modular PSU (rebadged seasonic). The aim was to have a pc ready for oculus rift cv1, which hopefully (fingers crossed) will be a 4k screen, and be out sometime later this year (though maybe cv1 will be 2k, and cv2 will be 4k).

Over the black friday/christmas period, I bought a 4790k, z97 board, 2xintel 730 ssd's in raid 0 config, and 16 gig of ram (which is overkill for gaming atm), which forms the base of the system, and should last me about 5 years (because intel isn't breaking speed records lately with each tick/tock). The only thing i've held off on is the graphics upgrade (running a single 760 from my old system atm).

My aim is to be able to run nvidia 'vr direct', so i'm aiming at 2 graphics cards, which each need to feed an effective 2k display (half of the 4k screen each). To do this I was going to go 2 x 980's. But i've held off to save up for big maxwell 1 inititially when they are released, then the 2nd when oculus cv1 comes out later this year (hopefully).

Anyway, I currently game on a single 144hrz 1080p monitor, though i'm often running nvidia 3d vision at 120(60 per eye)hertz. I'm just playing through my older games in 3d atm, as i've only just now finally started running my nvidia 3d vision kit, that I bought almost 4 years ago . So a single big maxwell will run most recent games at decent levels of detail in 3d, with the aim of not dropping below 120fps (otherwise it will stutter).

So, back to thread relevancy A 4790k plus 2 980's (manufacturer overclock) would average about 500w in games, and peak at 600w for short intervals. Which is fine for a 750w psu. I could also o/c the 4790k further towards 5gig, and overclock 2 980's further, and pull another 100w, which would still be ok.

Or... I could go 2 big maxwells, which at a guess, will pull about 225-250w each average, with peaks up to 300-325w (at a hopeful good guess). And because games these days are rarely cpu bounded, just run it at 4.4/4.5.

So, a small to no cpu o/c, combined with 2 big maxwells will average what? ... 650w. Peaking at 750w. (maybe/hopefully)

Now to the layperson, running this config on a '750w' psu would sound insane... But, having read the reviews, I know this psu can take 987 watts, and still be running (1338 at the plug!). http://www.hardwaresecrets.com/article/Antec-High-Current-Gamer-750-W-Power-Supply-Review/1141/8

 

[R-T-B]

I was told by some people here to get a 750W PSU when I upgraded to my R9 290X, now I'm thinking of swapping my old Rosewill 550W back in lol.

I never really use more than 50% of it, and while that's great for efficiency (prime territory for this PSU), that's about it.

 

[claylomax]

I undervolt my 290X and it uses even less power. The reason I have a 1000w psu is because I had GTX 480 SLI before.

 

[metalslaw]

I wrote up about 2-3 more paragraph's on my post, but I somehow deleted them, and undo didn't bring them back :/

Anyway, it was about the days of 1000w psu's being no longer required, in this day of greater and greater efficiency gains, in both cpu and gpu's (maxwell in particular is quite incredible).

These days, the only reason to get anything over 750w is if your running 3xsli/crossfire(around 1000w), or running a system heavily overclocked in 2xsli/crossfire.

For a single graphics card system , for most consumers running a decent system, a 500w power supply is almost overkill nowadays. 5 years ago, it was the norm. In saying that though, would I recommend less than 500w? No. Because even if they are using a cheaper cpu, or a cheaper gpu, in a few years time, the current high end cpu's will be on ebay at a very cheap price, and a cheap cpu upgrade on an older board is a good way to get a better system without spending much dough. Even just getting a person who hasn't overclocked before, and upping their system a fair amount, is a good upgrade for some people. And a 500w power supply covers these instances. Even a gpu upgrade, to an older 'more powerful' gpu via the cheap on ebay works.

I still have my old antec sonata system up and running as my everyday machine (and I also have a retired old gaming machine with same sort of specs). 500w antec earthwatts (rebadged seasonic before they went to delta). It's been through 2 cpu upgrades, and 3 gpu upgrades. has multiple aging harddrives. All cpu's were overclocked well, 2180e (3gig), then 7300e (3.33), then 8500e(3.8). And the last cpu I bought for my aging gaming pc was a e8600 a while ago. It cost me $50... and went to 4gig on air with lowish volts... lol I could have o'ced it further, but knew I needed something way better if I was to get my 3d vision up and running properly.

I reckon if skylake and pascal bring even greater efficiency gains, we could be looking at even less wattage psu's becoming the norm than now

I actually wonder if I we might end up at a (the good ol pentium standard of...) 250w power supply norm, within the next 10 years (for a decent consumer system)